This invention relates to an improved chair construction wherein the seat support and back support are independently adjustable within a range of angular positions and wherein selected positions of the supports may be releasably and effectively locked by an occupant of the chair by the operation of simple control means.
In the field of office and other working chairs it is well known that optimum ergonomic positioning of an occupant is determined by physical characteristics of the individual concerned as well as the type of operation intended to be undertaken by the occupant. Factors which have been recognized as being the major requirements for ergonomic positioning are height of the seat support, height of back support and the angular inclinations of the seat support and back support. In order to provide for different occupants and different activities it is well-known to make the above parameters adjustable.
In order to provide adjustment of the angular inclination of the seat support or back support for a working chair, various clutch operated mechanisms have been developed for locking the seat support or back support into a selected angular position. Examples of such constructions are disclosed in U.S. Pat. Nos. 4,062,587, 4,198,094 and International Patent Application W081/00044. Such clutch operated mechanisms have been further developed to provide simultaneous adjustment of the seat support and back support of a chair and which lock those supports into selected angular positions. An example of such mechanism is disclosed in U S. Pat. No. 4,636,004.
However known mechanisms for providing angular adjustment of both the seat support and back support of a chair are complex in construction and assembly as well as providing limited angular movement of the seat support in particular. Moreover the known clutch constructions are bulky and not always effective in maintaining a seat support and a back support in a selected position.
The present invention provides an improved apparatus for supporting a seat of a working chair which provides independent angular adjustment of a seat support and back support and which is simpler than prior constructions while providing a broad range of angular positions of the seat member and back member and effective locking of those members in a selected angular position.